1. Field of the Invention
The present invention relates to orthodontics and more particularly to an appliance which may be removably fitted into place by the wearer and which incorporates permanent magnets for the purpose of generating the desired corrective forces.
2. Description of the Prior Art
Prior to the present invention, many types of appliances incorporating a variety of arrangements of magnetic elements for developing corrective forces have been proposed. Also, magnetic elements have been used in combination with dentures for retaining the latter in the mouth. Representative of this prior art are the following U.S. Pat. Nos. 2,543,773; 2,709,301; 3,353,271; 3,798,770; 3,984,915; 4,017,973 and 4,284,405.
As to those magnetic devices used normally for retaining dentures in position, either magnets are located in the gum with an opposite and attracting magnet in the denture, or like magnets for repulsion are located in the upper and lower dentures. Magnets have also been used to locate dentures in the proper position in the mouth or to hold side-by-side dentures in the correct position. None of these denture arrangements are concerned with the matter of applying corrective forces to live teeth normally treated by an orthodontist.
As to orthodontic appliances, magnets have been attached to teeth by direct bonding, by means of conventional bands and also by means of arch wires. For purposes of this invention, these are regarded as permanent or semi-permanent attachments. Another technique is to employ two juxtaposed magnets, one being mounted on a biting plate and the other on a patient's tooth as disclosed in U.S. Pat. No. 3,984,915. Such magnets in the usual form are elongated with the opposite ends serving as magnetic poles, the pole areas being relatively small. As attached to the teeth, the magnets are usually polarized in end-to-end relation according to the kind of corrective force desired. Further, such magnets are disposed in one of two general arrangements, one in which the magnets interact between teeth in the same dental arch and the other in which they interact between arches. In both, they are permanently affixed as contrasted with being removable by the wearer. In both, the magnetic poles must be rather accurately aligned due to the small pole areas in order to maintain application of the desired corrective force over relatively long periods of time, any misalignment between poles resulting in development of improper forces or of no forces at all. Maintaining alignment as between arches is especially a problem since normal jaw movement causes misalignment of the poles resulting in generation of forces in directions other than that desired.